100215 07:02:24 mysqld started
/usr/libexec/mysqld: Can't read dir of '/tmp/' (Errcode: 13)
/usr/libexec/mysqld: Can't create/write to file '/tmp/ibyP1qUC' (Errcode: 13)
100215 7:02:24 InnoDB: Error: unable to create temporary file; errno: 13
100215 7:02:24 [ERROR] Can't init databases
100215 7:02:24 [ERROR] Aborting
100215 7:02:24 [Note] /usr/libexec/mysqld: Shutdown complete
100215 07:02:24 mysqld ended
One of my servers was rebooted for some reason and all sites and e-mail accounts were down because the database could not be connected. The first thing I checked was mysqld of course and it was not running. The above was revealed in /var/log/mysqld.log
I was starting to panic and wondered if the server was compromised and I even checked /var/lib/mysql to make sure all the database data was still there.
chown root.root /tmp
chmod 1777 /tmp
And of course be sure that you start MySQL again.